set -u

SLOTS="${CPU_RUN_SLOTS:-3}"

THREADS="${CPU_RUN_THREADS:-3}"

MAXWAIT="${CPU_RUN_MAXWAIT:-3600}"

DIR="${CPU_RUN_SLOT_DIR:-/tmp/cpu_run_slots}"

mkdir -p "$DIR" 2>/dev/null || true

export CPU_RUN_ACTIVE=1

export OMP_NUM_THREADS="$THREADS" OPENBLAS_NUM_THREADS="$THREADS" MKL_NUM_THREADS="$THREADS" \

       NUMEXPR_NUM_THREADS="$THREADS" VECLIB_MAXIMUM_THREADS="$THREADS"

run() {

  if command -v ionice >/dev/null 2>&1; then

    exec nice -n 15 ionice -c3 "$@"

  else

    exec nice -n 15 "$@"

  fi

}

waited=0

while :; do

  for i in $(seq 1 "$SLOTS"); do

    exec 9>"$DIR/slot$i"

    if flock -n 9; then

      echo "[cpu_run] slot $i/$SLOTS acquired (threads=$THREADS, nice 15) → $*" >&2

      run "$@"

    fi

    exec 9>&-

  done

  if [ "$waited" -ge "$MAXWAIT" ]; then

    echo "[cpu_run] all $SLOTS slots busy ${MAXWAIT}s - running un-slotted (still capped+nice'd): $*" >&2

    run "$@"

  fi

  sleep 2; waited=$((waited+2))

done